i’d say you can be atheist and believe in ghosts/spirits, that’s pretty different from divine beings

the core thing about divinity is power, power to do things or power to have done things in the past or future. spirits and ghosts generally have power comparable to living people, so the lack of obvious evidence for their existence isn’t anywhere near as big of an issue as with deities capable of altering the fabric of reality.

it’s not that incongrous that we’d fail to notice things that can barely interact with us, but an explicitly omnipotent and omniscient god? they can damn well write “hey ho here i am!” in the clouds.